traction control PORSCHE 911 GT2 2008 5.G Information Manual

· 15 · · 14 ·The 911 GT2 |
The 911 GT2
Drive is transmitted through a pre-
cision six-speed manual gearbox.
Rear-wheel drive provides driving
dynamics that are similar to those
of a racing car. In the 911 GT2,
Porsche also uses a special system
for conventional manual transmis-
sion: the Launch Assistant (see
page 38) – for maximum accelera-
tion from a standing start.
For a sporty but still comfortable
drive, particularly for this type of
sportscar, the standard suspension
features variable damping providedby Porsche Active Suspension
Management (PASM, see page 48).
This active damping system offers
a wide range of benefits including
greater performance and comfort.
Also standard is Porsche Stability
Management (PSM, see page 50).
For the first time, the integrated
control systems for lateral and lon-
gitudinal dynamics, stability control
(SC) and traction control (TC) can
be fully disabled in two stages for a
more natural drive. This means thecar can also be enjoyed to maxi-
mum effect on the racetrack.
The one-piece 19-inch GT2 alloy
wheels of the 911 GT2 are fitted
with road-legal sports tyres as
standard. In size 325/30 ZR 19 on
the rear, these are 20 mm larger
than on the 911 Turbo. The special
tread and compound enable
tremendous lateral acceleration
and higher cornering speeds as
well as precision handling and
turn-in characteristics on either
road or racetrack. A range ofsetup options is available for
racing use, including ride height,
camber, toe angle and front/rear
anti-roll bars.
Developed in motorsport, and
standard on the 911 GT2 is the
Porsche Ceramic Composite
Brake (PCCB, see page 58).
The discs are made from specially
treated carbon fibre and are
approximately 50 % lighter than
comparable metal alternatives.
The results: better brake perfor-mance, greater agility and lower
fuel consumption.
Sports bucket seats (see page 72)
with folding backrest, integral
thorax airbag and manual fore/aft
adjustment, are fitted as standard.
A perfect driving position is essen-
tial in a car with the performance
potential of the 911 GT2. The latest
Porsche Communication Manage-
ment (PCM, see page 76) is also
fitted as standard. This features
a new 6.5-inch touchscreen for
intuitive control.We believe that you don’t have
to exploit the full potential of
the 911 GT2. But you may well
choose to.

· 39 · · 38 ·
The 911 GT2 |Drive
The six-speed manual gearbox in
the 911 GT2 is specifically
designed for the high engine
performance. The individual ratios
are carefully matched to the spe-
cific characteristics of the engine.The gear-lever throw is short and
precise, enabling fast and
accurate gearshifts.
A typical feature of the 911 GT2
is the Launch Assistant – for maximum acceleration from a
standing start. The clutch and
accelerator are depressed when
the vehicle is stationary.
When a
boost pressure of approximately
0.9 bar is displayed in the instru-ment
cluster, release the clutchas
quickly as possible and maximum
a
cceleration automatically ensues.
Normally on a turbocharged vehicle
with manual gearbox, the boost
pressure under acceleration from
a standing start is relatively low.
The turbo effect is delayed as
the engine gathers speed and
the boost pressure starts to build.On the 911 GT2, this initial delay
is reduced. While the car is still
stationary, the fuel injection is
modified to help the engine reach
maximum output earlier. The boost
pressure is significantly increased
and the engine readied for a faster
start.
A specially designed traction
control system adapts the acceler-
ation procedure automatically
in the ECU to ensure optimum
traction. The clutch remains
engaged. This reduces load and
prevents high clutch wear. The
power is transmitted directly to
the road via the rear axle.
The gearbox is combined with
a cable linkage and dual-mass fly-
wheel offering added comfort and
precision. The close ratio spread
enables powerful acceleration
within the optimum engine power
band.
Steel baulk rings on gears two to
five ensure a precise gearshift
action even under extreme loads.Cooling is provided by an add-
itional oil-to-water heat exchanger
and spray lubrication. Both of
these features are essential for
durability in endurance racing
conditions.
Other standard features include
a limited-slip differential with
asymmetrical lock factor. Offering
better traction and handling
when exiting a corner, it applies a
higher proportion of drive torque
to the loaded outer rear wheel.
The term ‘asymmetrical’ means
that one lock factor is applied
when cornering under power
(28 %), and another when braking
for a corner (40 %).
Maximum response to minimum effort.
Transmission.

· 49 · · 48 ·
The 911 GT2 |Chassis
The 911 GT2 is fitted with Porsche
Active Suspension Management
(PASM), an electronic damper
adjustment system. This active
damping system offers continuous
adjustment of individual damping
forces based on current road
conditions and driving style.
The driver can choose from two
basic setup modes: ‘Normal’ and
‘Sport’. ‘Normal’ mode is designed
for general road driving and wet
circuit use. ‘Sport’ mode enables
greater lateral acceleration and
increases traction on the race-
track.
In either mode, the system
responds to changing loads by
automatically applying the optimum
rate on each individual damper
from a range of predefined options.Various sensors are used to
monitor the movement of the body
during acceleration, braking and
cornering manoeuvres, as well as
on poor road surfaces. The PASM
control unit then evaluates this
data and modifies the damping
force on each individual wheel in
accordance with the selected
mode. The results are a reduction
in pitch and roll as well as con-
sistent road contact on all four
wheels.
If ‘Sport’ mode is selected using
the PASM button identified by a
damper symbol, the suspension is
set to a harder damper rating that
is specially designed for perform-
ance driving. If the quality of the
road surface falls below a certain
threshold, the system immediatelychanges to a softer rating within
the ‘Sport’ setup range. This
adjustment enhances occupant
comfort as well as traction and
grip. When the road surface
improves, PASM automatically
reverts to the original, harder
rating.
Rebound in ‘Sport’ mode –
damper piston with bypass
valve closedRebound in ‘Normal’ mode –
damper piston with bypass
valve open
Compression in ‘Normal’ mode –
damper piston with bypass
valve open
Compression in ‘Sport’ mode –
damper piston with bypass
valve closed
Redefining ‘normal’.
Porsche Active Suspension Management (PASM).

· 51 · · 50 ·The 911 GT2 |
Chassis
Some things never change,
including driver expectations of
a 911 GT2 : sports-oriented
performance, a direct response
and impressive power.
So Porsche Stability Management
(PSM) has been specially adaptedfor the 911 GT2. In addition to
ABS, the package includes two
automatic driver aids: stability
control (SC) and traction control
(TC).
Stability control (SC), which is
responsible for lateral dynamics,uses a range of sensors to moni-
tor the direction, speed, yaw
velocity (speed of rotation around
the vertical axis) and lateral
acceleration of the car. Using
this information, it is possible to
calculate the actual direction of
travel at any given moment. If thecar begins to oversteer or under-
steer, selective braking is applied
on individual wheels to restore con-
trol in critical driving scenarios.
Traction control (TC), with its
integrated ABD (automatic brake
differential), ASR (anti-slip regula-
tion) and EDC (engine drag-torque
control) functions, is responsible
for the longitudinal dynamics of the
car. Configured for sports-oriented
driving, traction control improveshandling under acceleration on
surfaces with inconsistent grip.
It also prevents the rear from
‘stepping out’ if a wheel loses
traction under full power. The
trigger threshold is relatively high,
which means it is rarely employed
in normal dry conditions.
A unique feature of PSM on
the 911 GT2 is that the control
interventions are delayed and
can be disabled completely in
two stages – for deliberate per-
formance handling.
Stage 1 disables the stability con-
trol (SC) via the ‘SC OFF’ switch in
the centre console. In ‘SC OFF’
mode, the control system does
not intervene if the car goes off-
course in the lateral direction,
which means the throttle can
be used to help steer the car.
Traction control (TC) is still active
in this mode.
Stage 2 disables the traction con-
trol as well via the separate
‘SC+TC OFF’ switch, giving the
driver full command of the vehi-
cle. Another unique feature is the fact that stability control
remains disabled in stages 1 and
2 even when the ABS is required
under braking. Specially develop-
ed for the 911 GT2, this revised
system strategy means the car
can also be enjoyed to maximum
effect on the racetrack.
The anti-lock braking system
(ABS 8.0) is integrated in PSM
and remains active, irrespective
of which settings have been
selected. ABS ensures a relatively
short braking distance and thus
enhanced safety.
It’s good to know who’s in control.
Porsche Stability Management (PSM).

· 109 · · 108 ·The 911 GT2 |
Index
Index
A
ABS 51
Air conditioning, automatic 69
Airbags 62
Alarm system 75
Anti-theft protection 75
Audio system 76
B
Bi-Xenon lighting system 56
Bodyshell structure 60
BOSE® Surround
Sound System 80
Braking system 58
C
Catalytic converters 34, 85
Charge-air cooling 16
Chassis 42
Chrono Package Plus 75, 92
Clubsport package 64, 92
CO
284
Colours 88
Comfort 66
Communication 76, 96
Cruise control 74
D
Design 16
Drive 18
Dual-mass flywheel 39
E
Electronic logbook 78
Engine 20
Engine cooling 26
Engine management system 36
Environment 82
Exhaust emission control 85
Exhaust system 34
Expansion intake manifold 32
Exterior 91
F
Factory collection 100
Fire extinguisher 64, 93
Front axle 44
Fuel supply 35
Fuel system 35, 85
G
Gearbox, manual 38
GSM telephone module 78
H
HomeLink®74
I
Ignition system 35
Instruments 68
Interior 68, 93
Interior materials 70, 95
K
Knock control,
cylinder-specific 36
L
Launch Assistant 38
Leather 89, 95
Lightweight design 24
Loudspeakers 79, 80
Lubrication, dry-sump 25
Luggage compartment 74
M
Mobile phone preparation 79
N
Navigation module 77
Noise 85
O
Oil supply 25
On-board computer 69
Oxygen-sensor control 34, 85
P
ParkAssist 74, 90
Personalisation 86
Porsche Active Suspension
Management (PASM) 48
Porsche Ceramic Composite
Brake (PCCB) 58
Porsche Communication
Management (PCM) 76
Porsche Side Impact
Protection (POSIP) 62
Porsche Stability
Management (PSM) 50
R
Ram air principle 17
Rear axle 45
Rear wing 17
Recycling 84
Roll cage 64, 92
S
Safety 54
Safety, active 56
Safety, passive 60
Seats 72
Seats, adaptive sports 73, 92
Seats, sport bucket 15, 72
Service 102
Servicing 85
Six-cylinder twin-turbo
boxer engine 20, 24
Sound Package Plus 79
Sport tyres 46
Stability control (SC) 14, 50
Steering 52
Steering wheel 71
Storage compartments 73
T
Technical data 106
Telephone module 78
Traction control (TC) 14, 50
Transmission 38
Turbocharger 28
TV tuner 78
Tyre Pressure
Monitoring (TPM) 47
U
Universal audio interface 79
V
Variable Turbine
Geometry (VTG) 28
VarioCam Plus 26
Vehicle tracking system 75
Voice control system 78
W
‘Welcome Home’ lighting 74
Wheels 46